This application claims the priority benefit of Taiwan application Ser. No. 89122659, filed Oct. 27, 2000.
1. Field of Invention
The present invention relates to a vision system. More particularly, the present invention relates to a luminance correction system of image used in an imaging device.
2. Description of Related Art
Displaying appliance is widely used in our daily life. Particularly, a TV set or a computer system always need a displaying appliance, so that an image can be displayed on the screen of the displaying appliance, and thereby a user can see the image on the displaying device. Moreover, the displaying appliance can also be a projecting type, which can project an image onto a screen.
However, no matter which type of the displaying appliance, the displayed image always needs to be sense by the user""s vision organ, so as to recognize the content of the image. In this situation, the luminance of the environment can affect the vision effect for the user. Particularly, our eyes have different responses for the color in frequency at different degrees of luminance. Usually, a light can be de-coupled into three components of red, green, and blue. This allows the color correction can be corrected by the three components of red, green, and blue, respectively. FIG. 4 is a drawing, showing the eye""s response with respect to frequency range of visible color under a bright and dark environment, according to the data provided by Commission Internationale De L""eclairage (CIE). In FIG. 4, the solid curve represents the vision response curve under a bright environment, while the dashed curve represents the vision response curve under a dark environment. The horizontal axis is the quantity of light wavelength, the vertical axis represent the relative response. The red light has a wavelength of about 700 nm, the green light has a wavelength of about 550 nm, and the blue light has a wavelength of about 480 nm. As shown in FIG. 4, the response for different environment luminance is clearly different.
As depicted above, the displaying appliance under different environment luminance, the displaying appliance needs different degrees of luminance contrast ratio (CR) and variance of color saturation. The conventional method to correct the color luminance needs to be adjusted by the user through a software and an electrical feedback circuit. FIG. 1 is a diagram, schematically illustrating a conventional control system on a LCD displaying system. In FIG. 1, the LCD displaying system has a luminance control circuit 100. An LCD 110 is coupled to the luminance control circuit 100. The luminance control circuit 100 also coupled to a central process unit (CPU) 102 and other peripheral devices 104 through a system data bus. The luminance of the LCD 110 is controlled by the luminance control circuit 100. A photodetector 108 can detect the luminance of the environment, so as to determine the luminance of the LCD 110. User can adjust the luminance of the LCD 110 by the control button 106, according to the user""s preference. In this conventional skill, the color components of luminance of the LCD are adjusted at the same time. There is no individual consideration with respect to different colors under different luminance. Moreover, the result of luminance is still needing an adjustment through the control button 106 by the user. One of the drawbacks in this conventional method is that the eye response for different color under different environment luminance cannot be properly included in adjustment.
In the conventional skills, another method is proposed to correct color through the three components of red, green, and green (RGB). FIG. 2 is a drawing, schematically illustrating a color control system on a TV cathode-ray tube through a color temperature. In FIG. 2, the color control system includes a color decoder 112, used to decode a video signal into three components of RGB. The three color components of RGB are inputted into amplifiers 114a, 114b and 114c associating with nonlinear amplifications of red signal, green signal, and blue signal, respectively. Since the color temperature of the cathode-ray tube (CRT) 118 usually affects the color intensity of the each individual color. When the inputs of the red and green signals are greater than a predetermined value with respect to white color, the amplifications are adjusted to compensate the effect from the color temperature. However, the blue light remains without change. Then, three color signals of RGB are inputted to a video processing circuit 116 and then inputted to the CRT 118. In this conventional skill, it uses the three color components to adjust the color temperature of the CRT. However, this conventional skill can only be used in the control of CRT. It also cannot effectively adjust individual response for different colors.
The invention provides an intelligent luminance correction system used in a vision system. The invention can individually compensate luminance of the three basic color components of RGB for visual response under different environment luminance. There invention can automatically adjust the brightness of each color component without hand operation by user.
The invention provides an intelligent luminance correction system used in a vision system. The vision system includes a video decoder, used to receive a video signal and decode the video signal into three basic components of red, green, and blue. A photodetector is used to detect the luminance of the current environment, so as to export a reference signal. A color correction circuit is used to receive the reference signal and the three components of RGB. The color correction circuit also stores a vision response curve at dark condition and a vision response curve at bright condition, so that the color correction circuit can determine one curve of the vision response curve at dark condition and a vision response curve at bright condition according to environment luminance indicated by the reference signal. The three components of RGB thereby are corrected individual. After correction, the color correction circuit exports the corrected three components of RGB to a display.
In the foregoing, the invention can also be used in a projection device.
In the foregoing, the color correction circuit can further include a control software to individually compensate the three color components.
In the foregoing, the vision response curve at dark condition and the vision response curve at bright condition are taken according to the organization of CIE.
The invention also provides a method for adjusting image luminance. The method includes providing a video signal having three components of red, green, and blue. The method also includes detecting an environment luminance and accordingly generating a reference signal. A vision response curve at bright condition and a vision response curve at dark condition are provided. According to the reference signal, one of the vision response curve at bright condition and a vision response curve at dark condition is then chosen as a correcting vision response curve. The correcting vision response curve is used to individually correct the three components of red, green, and blue. A display is provided, and receives the three components of red, green, and blue for displaying the video signal.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.